Tension device for paint mills



March 31, 1931; E. PETERS 1,793,627

TENSION DEVICE FOR PAINT MILLS Filed Sept. 27, 1928 HHH Patented Mar. 31, 1931 UNITED STATES PATENT OFFE ELMER PETERS, OF RIOI-IMOND HILL, NEW YORK, ASSIGNORTO KENT MACHINE "WORKS, INC., A CORPORATION OF NEW YORK TENSION DEVICE FOR PAINT MILLS Application filed September 27, 1928. Serial No. 308,612.

This invention relates to improvements in paint mills of the type in which the pigment or material is ground between two flat cylindrical stones placed one above the other and in contact with each other. The pigment is caused to flow outward between the stones, of which the lower one is rotatedso as to grind the pigment against the upper stone.

In order to grind the material or pigment to the required degree of fineness tension must be put on the stones. To this end the lower stone is usually adapted to be lifted into contact with the upper stone to obtain the desired pressure or tension between the stones.

Heretofore it has been a matter of experi. ence or guesswork on the part of the mill hand or operator to determine the pressure required and adjust the machine accordingly, and as a result real grinding efliciency has been a matter of skill and of chance depending upon the operator, and the results have not been uniform or standard for the same kind of material.

The object of this invention is to provide a tension device adapted to be attached to standard types paint mills whereby a uniform standard tension may be automatically applied to the stones as required for certain kinds of materials to be ground, irrespective of whether a certain grinding operation is interrupted or not. The invention also includes as a feature the automatic maintenance of a given pressure or tension on the stones irrespective of wear.

Accordingly the invention is embodied in a tension device for paint mills constructed and arranged as hereinafter set forth and as illustrated in the accompanying drawing in which Fig. 1 is a view in diagrammatic outline of a standard paint mill equipped with a tension device embodying the invention, details and certain parts being omitted and with parts in section.

Fig. 2 is an enlarged sectional detail View of parts of the tension device.

Fig. 3 is a bottom view of Figure 2.

Referring to the drawing the reference numeral 5 denotes the upper fixed grinding stone and 6 is the lower grinding-stone. The upper stone is suitably supported in a general frame work 7. The lower stone 6 is supported on an upright shaft 8 supported in cross members 9 and 10. The stones are of the usual annular shape. The material to be ground is admitted in the central opening or inlet at 11 and flows down over the cone shaped hub 12 of the lower stone and then out between the stones and is removed by any suitable means not shown.

The shaft 8 rotates the stone 6 by means of suitable driving means as indicated at 13. The shaft itself is driven by means of bevel gears 14 and 15 from a main driving shaft 16 to which power. is applied in any suitable manner. The bottom of the shaft 8 rests within a vertically movable socket 17 which is raised and lowered by means of a bar 18 pivoted at 19, and which bar extends outside of the frame work 7 toone side of the machine.

To the other end of the bar 18 there is pivoted at 20 a rod 21 which extends upwardly and carries a head 22 within the casing 23 of the tension device 24. To the side of the framework 7 there is secured a bracket 25 which forms a bearing fora vertical tension adjusting rod 26. The latter extends down-- ward into the casing 23 and carries a plunger like member 27.

A spring 28 is interposed between the plunger 27 and the casing 23. The spring tends to push the casing upwards and lift the rod 21, hence tends to lift the bar 18, shaft 8 and the lower stone 6. 30 is a handwheel in threaded engagementwith the tension rod 26. a The tension device members are constructed and assembled as follows, see Figures 2 and 3. The casing 23 has an open bottom forming three radially extending teeth or lugs 32. The head 22 is screwed on to the lower rod 21 for purposes of adjustment and is formed with'three teeth or projections 33. The plunger 27 is likewise formed with three lugs 34. All of the lugs or teeth are of course spaced'equidistantly circumferentially of the respective parts.

In assembling, the spring is first put into the casing, then the plunger 27, whose lugs 34 pass in through the spaces 35 between the casing teeth 32. Thereafter the upper tension rod is inserted from above and screwed into the plunger. Next the head 22 on the rod 21 is put into the casing, its teeth 33 passing between the teeth 32 of the casing. Then the rod 21 and head 22 is given a slight turn to position the teeth 33 of the head to lie above and on the teeth 32 of the casing between ribs l0 as shown in Figures 2 and 3. Conseuently rotative movement between the lower rod 21 and the tension device is impossible.

The rod 21 is then connected to the bar 18 and the tension rod 26 put up through the bracket 25 and the handwheel 30 is screwed on. The casing 23 is provided with a slot 4.1 and a spacer 42 moves in said slot and is screwed fast to the plunger 27. The side of the casing above the slot is provided with a scale at 43 and a pointer 1% is also secured to move with the plunger 27 as seen in Figure 2. It follows that relative rotative movement between the plunger 2'? and casing 23 is impossible.

In operation, in order to adjust the tension between the stones, that is lifting the shaft 8 and the lower stone, the handwheel 30 is 1'0- tated which causes the tension rod and plunger to be lifted relative to the casing which cannot turn. Likewise the head 22 and lower rod 21 cannot turn because of the connection at 20. The casing therefore stands still while the plunger 27 moves upward. The spring therefore is being compressed between the casing, which has become a part of the lifting bar 18 and the plunger and as the bar is lifted increasing tension is put on the stones as is obvious.

For a given pigment the tension will be predetermined by experiment or otherwise and as the pointer moves upwards over the scale to stop position, the scale will indicate the desired tension for the particular pigment. \Vhn therefore another like batch is to be ground the tension therefor is quickly .obtained by adjusting the tension to the known degree indicated by the scale. Thus uniform tension for a particular grinding operation is assured.

Again, during the grinding operation, the spring will of course take up and compensate for wear and inequalities in the stones and automatically maintain the desired degree of tension.

The tension device as herein disclosed is simple in design and construction and emcient in operation. The particular detailed construction may be changed to suit the type of machine to which it is to be attached. Other details of construction and arrangements may also be varied to suit local requirements. On the other hand, the tension device may be made regular equipment of certain sizes and kinds of grinding machines and kept ready in stock.

I claim 1. In a paint mill a pair of co-operating grinding stones, a device for automatically causing a predetermined degree of pressure to be maintained between the stones during the grinding operation comprising a lever for moving the one stone relative to the other, a fixed bracket, a compression adjusting screw in threaded engagement with said bracket, a casing, one end of said screw extending within the latter, a piston on the end of the screw within the casing, a spring acting between said piston and the casing and a member supported in the casing and connected to the said lever.

2. In a paint mill a pair of co-operating grinding stones, a device for automatically causing a predetermined degree of pressure to be maintained between the stones during the grinding operation comprising a lever for moving the one stone relative to the other, a fixed bracket, a compression adjusting screw in threaded engagement with said bracket, a casing, one end of said screw extending within the latter, a piston on the end of the screw within the casing, a spring acting between said piston and the casing, a

member detachably supported in the casing and connected to the said lever and visible means indicating compression of the spring.

ELMER PETERS. 

